High-Resolution Acoustic Ejection Mass Spectrometry for High-Throughput Library Screening

Authors

  • N Hoxie
  • DR Calabrese
  • Z Itkin
  • G Gomba
  • M Shen
  • M Verma
  • JS Janiszewski
  • JH Shrimp
  • KM Wilson
  • S Michael
  • MD Hall
  • L Burton
  • TR Covey
  • C Liu

Abstract

We present a novel approach for high-throughput quality assessment of drug candidate libraries using acoustic ejection high-resolution mass spectrometry (AEMS). This method facilitates sample introduction from 1536-well plates by dispensing 2.5 nL droplets into an Open Port Interface (OPI) with pneumatically assisted electrospray ionization, achieving a throughput of one sample per second. Both positive and negative ionization modes are utilized to enhance compound coverage within a protease inhibitor-focused library. We introduce specialized software for efficient data interpretation in the 1536-well format and propose a high-throughput quantification method (HTQuant) that obviates the need for internal standards, maintaining workflow efficiency. This quantitation approach relies on high peak area reproducibility, demonstrated to be 4.4% across a 1536-well plate analysis. Additionally, we present a troubleshooting strategy based on background ion current signals. Comparative analysis with the industry-standard LC/PDA/ELSD/MS method reveals that AEMS offers similar compound coverage but with a 180-fold increase in throughput. Both methods identified unique compounds not detected by the other, despite using the same ionization process. The applicability of this method extends beyond the initial case study, as evidenced by comparisons with a chemically diverse library. This capability is particularly relevant given the increasing use of artificial intelligence in drug discovery, which demands extensive high-quality data for predictive modeling. The molecular structures of the 872-compound library analyzed are included to facilitate the correlation of molecular structures with ionization efficiency and other parameters, marking an initial step towards this goal.

Scientific Focus Area: Molecular Pharmacology

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